Measuring the Z Dimension

Fig 1: Measuring Z Height Dimension

Courtesy of GENERAL MOTORS COMPANY

Measurement Definition 

Z Height: The vertical distance between the midpoint center of the ball joint cup lower surface (Point A) to the midpoint of the lower control arm bushing lower flat surface between the vertical attachment bolt heads (Point B).

Fig 2: Point A - Midpoint Center Of Ball Joint Cup Lower Surface

Courtesy of GENERAL MOTORS COMPANY

Point A is the midpoint center of the ball joint cup lower surface.

Fig 3: Point B - Midpoint Of Lower Control Arm Bushing Lower Flat Surface Between Vertical Attachment Bolt Heads

Courtesy of GENERAL MOTORS COMPANY

Point B is the midpoint of the lower control arm bushing lower flat surface between the vertical attachment bolt heads

Use the following procedures to measure the Z dimensions:

NOTE:

The left and right Z height differences should be no more than 10 mm (.39 in).

1. Push the front bumper down a minimum of 25 mm (1 in). Perform this step three times.
2. Measure and record the trim height per the "Measurement Definitions" above.
3. Lift the front bumper a minimum of 25 mm (1 in). Perform this step three times.
4. Measure and record the trim height per the "Measurement Definitions" above.
5. The true Z height dimension is the average of the measurements taken in steps 2 & 4. Refer to Trim Height Specifications 
6. If these measurements are out of specifications, inspect for the following conditions:
   • Worn or damaged suspension components
   • Collision damage